AMPHETAMINE EFFECTS ON STRIATAL NEURONS - IMPLICATIONS FOR MODELS OF DOPAMINE FUNCTION

Models of dopamine function based on the bidirectional neuromodulation of afferents (40,95) were tested by determining whether cortical abla tion would affect the excitatory and inhibitory effects of amphetamine (AMPH) on striatal neurons in freely moving rats. By minimizing pre a nd post-AMPH behavioral differences, behavioral clamping revealed that cortical ablation blocked the capacity of AMPH to produce a net excit ation of striatal neurons that had shown AMPH-induced excitations unde r non-clamping conditions. Cortical ablation did not affect AMPH-induc ed neuronal inhibitions under behavioral clamping conditions. These re sults suggest that AMPH, possibly by enhancing dopaminergic neuromodul ation, facilitates or inhibits the activity of neurons that respective ly receive substantial or little cortical input. Thus, the findings su pport models that assign dopamine the capacity to increase the gain of neuronal information processing. Basic research relevant to these mod els is reviewed and potential clinical implications are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.